Question

Indicate whether each of the following fits qualitative (qual) or quantitative (quant) traits.  (1.5)

a) more likely to be affected by environmental factors ___________                       b) tend to show a range of phenotypes _________

c) tend to be an “all or nothing” phenotype expression ____________                    d) hair color ______________

e) presence or absence of Huntington’s disease ____________                                f) severity of Huntington’s disease ___________

Which of the following are contributions made by Mendel to the field of genetics?  Circle all that apply.  (1)

a) He considered genes to be physical things passed from parent to offspring.

b) He described the concepts of dominant and recessive traits.

c) He discovered the ability of genes to cross over together and identified the phenomenon of “linkage”.

d) He hypothesized that each gene in a pair is passed on to offspring independently of other gene pairs.

e) He discovered the inheritance pattern of invisibility in gnomes.

A daughter shows a sex-linked recessive trait.  Which of the following sets of parents could produce the affected daughter?  (Circle all that apply)  (1) (Use the rules on the handout)

        a)     Carrier father, carrier mother                                                      b) Affected father, affected mother

3. Affected father, carrier mother                                                   d) Carrier father, affected mother  

A son shows a sex-linked dominant trait.  Which of the following sets of parents could produce the affected son?  (Circle all that apply)  (1)  (Use the rules on the handout)

1. Affected mother, affected father                                                c) Unaffected mother, affected father
2. Affected mother, carrier father                                                   d) Unaffected mother and father

Answer 1

A. Quantitative traits as these traits usually change in response to the environment.

B. Qualitative as a quantitative trait is one that has a measurable phenotypic variation.

C. Qualitative traits are phenotypes that are expressed in an all or nothing fashion

D. Hair color is quantitative as quantitative traits tend to be more complex and are usually controlled by multiple genes. Hair color is also controlled by two genes.

E. Qualitative trait as a qualitative trait is the presence or absence of the disorder.

F. Quantitative as severeness of the disorder is a quantitative trait.

2. Statement B, D, and E are correct. A is wrong as at that time Mendel didn't know about genes. C is wrong as Mendel didn't discoer linkage but Willian Bateson did.

3. Options A and B are correct. Females can get an X-linked recessive disorder, but this is very rare. An abnormal gene on the X chromosome from each parent would be required since a female has two X chromosomes. This could occur in the two scenarios below. In each pregnancy, if the mother is a carrier and the father has the disease and  If both the mother and the father have the disease.

4. Options A andC are correct. In case of X linked dominant trait affected mother will give rise to effected sons.